Conventionally, in Japanese Unexamined Patent Publication (KOKAI) No. 2-246,823, a viscous heater is disclosed which is utilized as a heating apparatus for a vehicle. In this viscous heater, a front housing and a rear housing are disposed so as to face with each other, and are fastened by through bolts, thereby forming a heat-generating chamber and a water jacket therein. The water jacket is disposed around an outer region of the heat-generating chamber. In the water jacket, circulating water is circulated so that it is taken in through a water inlet port, and that it is delivered out to an external heating circuit through a water outlet port. In the front housing, a driving shaft is held rotatably via a bearing apparatus. To the driving shaft, a rotor is fixed so that it can rotate in the heat-generating chamber. A wall surface of the heat-generating chamber and an outer surface of the rotor constitute labyrinth grooves which approach to each other. In a space between the wall surface of the heat-generating chamber and the outer surface of the rotor, a viscous fluid, such as a silicone oil, is interposed.
In the viscous heater built into a vehicle heating apparatus, the rotor rotates in the heat-generating chamber when the driving shaft is driven by an engine. Accordingly, the viscous fluid is caused to generate heat by shearing in the space between the wall surface of the heat-generating chamber and the outer surface of the rotor. The thus generated heat is heat-exchanged to the circulating water in the water jacket. The heated circulating water is used at the heating circuit to heat a vehicle.
Moreover, in Japanese Unexamined Utility Model Publication (KOKAI) No. 4-11,716, a viscous heater is disclosed in which fins are projected into a water jacket. In this viscous heater, heat exchange can be carried out with a relatively high efficiency, because the fins enlarge a surface area of a wall surface constituting the water jacket.
However, in the viscous heater set forth in Japanese Unexamined Patent Publication (KOKAI) No. 2-246,823, heat exchange cannot necessarily be carried out fully, because the surface area of the wall surface constituting the water jacket is relatively small, and because there is a fear of short-circuiting or retaining the circulating water in the water jacket.
Likewise, in the viscous heater set forth in Japanese Unexamined Utility Model Publication (KOKAI) No. 4-11,716, heat exchange cannot necessarily be carried out fully, because there is a fear of short-circuiting or retaining the circulating water in the water jacket.
It is therefore an assignment to the present invention to provide a viscous heater which can carry out full heat exchange securely.